Identification of the Substance Active in Sheep Cell Agglutination Test for Rheumatoid Arthritis

Summary The active principle responsible for sheep cell agglutination test for arthritis was purified and concentrated by salt fractionation and by dialysis against solutions of low ionic strength. The most active fractions were precipitated as plasma was adjusted from a concentration of 9% to a concentration of 14% sodium sulfate, or from ionic strength 0.06 to ionic strength 0.04. The electrophoretic fraction most consistently present in the concentrate was beta globulin. The agglutination factor is adsorbed on fibrin and is inactivated during lyophilization of concentrates and by the addition of alcohol to arthritic plasma.